Radiographic apparatus which obtain sectional images through a reconstruction process include an X-ray CT (computed tomography) apparatus and an X-ray body section imaging apparatus. In the X-ray CT apparatus, sectional images are obtained by an X-ray tube (radiation emitting device) and an X-ray detector (radiation detecting device) rotating about the body axis extending longitudinally of a patient. In the X-ray body section imaging apparatus, as shown in FIG. 20, for example, sectional images are obtained by an X-ray tube 101 and an X-ray detector 102 making parallel translation in opposite directions along the body axis z of a patient M. In the case of the X-ray body section imaging apparatus, compared with the X-ray CT apparatus, the resolution of sectional images obtained is inferior, but there is an advantage that sectional images can be obtained through parallel translation. The image pickup mode adopted in such X-ray CT apparatus and X-ray body section imaging apparatus is an image pickup method effective for many sites such as the chest, joints and digestive organs.
On the other hand, there has been an X-ray apparatus in recent years which obtains X-ray images along the body axis of a patient by moving an X-ray tube and an X-ray detector in parallel to each other in the same direction along the body axis of the patient (see Patent Document 1, for example). The X-ray images obtained with this apparatus are projection data of projected X rays (projection images). Since the X-ray tube and X-ray detector move parallel to each other in the same direction along the body axis, the projection angle can be maintained at substantially the same angle. Therefore, X-ray images can be obtained of a long area (long X-ray images) in the longitudinal direction which is the direction of the body axis.
[Patent Document 1]
Unexamined Patent Publication No. 2004-236929 (pages 1-8, FIGS. 1, 6 and 10)